A368702 Numbers whose second arithmetic derivative (A068346) is a primorial number (A002110) > 1.

14, 186, 258, 322, 338, 3318, 3962, 5334, 6106, 7674, 8970, 9186, 9978, 10930, 11994, 12154, 12614, 12970, 13218, 13234, 14626, 15226, 15914, 16378, 17122, 18226, 18658, 19058, 19874, 20194, 20962, 21082, 21106, 21218, 44718, 49358, 57346, 58354, 75442, 76162, 81802, 87814, 95114, 102794, 113505, 114918, 130802

Offset

1,1

Comments

Numbers k for which A003415(k) is one of the terms of A327978.

Links

Table of n, a(n) for n=1..47.

Prog

(PARI)
A002620(n) = ((n^2)>>2);
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A068346(n) = A003415(A003415(n));
A276150(n) = { my(s=0, p=2, d); while(n, d = (n%p); s += d; n = (n-d)/p; p = nextprime(1+p)); (s); };
isA368702flat(n) = { my(u=A068346(n)); ((u>1)&&(1==A276150(u))); };
k=0; for(n=1, A002620(A002110(7)), if(isA368702flat(n), k++; write("b368702.txt", k, " ", n)));

Crossrefs

Cf. A002110, A003415, A068346, A327978.

Subsequence of A046100 and of A328244.

Sequence in context: A198650 A198657 A055759 * A368536 A275084 A086946

Adjacent sequences: A368699 A368700 A368701 * A368703 A368704 A368705

Keyword

nonn

Author

Antti Karttunen, Jan 09 2024

Status

approved